Studies into the molecular mechanisms of action of cholera enterotoxin on Y1 adrenal tumor cells in tissue culture will be continued. Inhibitors of energy-associated transport mechanisms will be employed to further delineate the association between toxin-induced activation of adenylae cyclase, morphological changes, and steroidogenesis. In addition, freeze-fracture electron microscopy will be employed to determine if cholera toxin effects intramembranous particle aggregation and gap-junction formation. Studies specifically dealing with the nature of the toxin-receptor site on Y1 cells will also be initiated. BIBLIOGRAPHIC REFERENCES: Donta, S.T., Kreiter, S.R., and Wendelschafer-Crabb, G.: Morphological and Steroidogenic Changes in Cultered Adrenal Tumor Cells Induced by a Subunit of Cholera Enterotoxin. Infect. Immun. 13:1479-1482, 1976. Donta, S.T.: Gastroenterologists on the Move: The Nature of Travelers' Diarrhea (Editorial). N. Engl. J. Med. 294:1340-1341, 1976.